Coatings may be applied on substrates to enhance the physical and optical properties of the substrate. For example, paper and paperboards used in the printing and converting industries may be subjected to a variety of operations, such as, for example, printing, cutting, creasing, folding, and/or gluing. Coated paperboards are widely used in the packaging industry, and a typical coating formulation may include one or more pigments, binders, and additives. Such coatings may serve to enhance physical, optical, and/or barrier properties of the products. Physical and/or optical properties may provide aesthetic appeal and/or functional benefits to packaging formed from the coated substrates. Paper and paperboard products may be very sensitive to moisture and moisture vapors, and barrier properties may provide a barrier against moisture, oil, water vapors, or gases.
Creasing and folding operations are important processes in the converting industry. However, creasing and folding may result in applying significant strains to the paper or paperboard substrates. Such strains challenge the mechanical strength of the substrates as well as any coating layers present on the substrates. For example, rupture occurring at creased and folded edges of the paper and paperboard products may weaken barrier properties of the substrate significantly and may diminish the overall aesthetic appeal of a packaging formed by the substrate. An inability to withstand these large strains may lead to rupture of folded edges, potentially resulting in large cracks or flaking-off of the coating layer or both.
Traditionally, coating layers with higher stiffness have been preferred, since higher stiffness coating layers may provide superior strength and/or reduction in the fiber usage for the substrate. However, stiffer coating layers may tend to increase the severity of cracking or flaking occurring at folded edges of paper or paperboards.
Therefore, it may be desirable to provide coating compositions that exhibit improved resistance to cracking and/or flaking when the substrates coated with the coating composition are folded, or improved performance when the substrates undergo printing or converting operations.